The present disclosure is directed to the improving laser based additive manufacturing through the use of structured powder particles as feedstock.
Laser based additive manufacturing methods can create near net shape components by selectively melting powder particles in a layer by layer fashion. The processing and resultant quality of the deposit is sensitive the powder feedstock which depending on the alloy in question can be subject to one or more of 3 main challenges.
One challenge is flammability. Most metals in powder form have ignition/explosion dangers requiring careful powder handling and costly safety/fire suppression systems.
Another challenge includes contamination. Certain alloys have a higher propensity to pick up moisture and other deleterious compounds from the atmosphere. When the powder is then rapidly melted and solidified in the additive process, the contaminants can evolve creating detrimental gas bubbles/blisters/pores in the build. While it is possible to keep powder sealed in an inert container prior to use, exposure to atmosphere occurs at the end of the build when the additive system is opened to extract the part and recapture unused powder for subsequent builds.
Another challenge is reflectivity. Some alloys have a high reflectivity causing much of the incident energy from the laser to be reflected. The consequence is that the additive system must run at either higher powers or slower speeds thus degrading the build efficiency.
Processes that remove surface moisture and contaminants from metal powders have been utilized. The desire to produce parts from feedstock by additive manufacturing processes having tailored structures with acceptable properties remains.